64- Prof. Meyen's Report of the Progress of 



2. All wood consists of a combination of liber and vessels 

 which belong to the air-productive system. The liber is the 

 osseous system, the spiral and dotted vessels are the tracheal 

 system of the vegetable organism. 



3. The liber is always formed earlier than the vessels. 



16. It has also been supposed and taught, that the wood of 

 ConifercE consists in the older annual rings entirely of vessels ; 

 however, we find in each, even in the oldest annual ring, a 

 very thin layer of liber, which has been overlooked on account 

 of its thinness. 



19. Liber and wood independently, and the combination 

 of both parts in their yet soft condition, is called alburnum. 



20. There also originates, with every new ligneous layer, 

 a new thin stratum of parenchyma, at the exterior surface of 

 the new liber and interior side of the old, which at first is full 

 of sap, and subsequently passes over into suberose tissue, and 

 imparts to the dead rind the brown colour; whence we also 

 find in the cortex layers formed, which consist alternately of 

 liber and cork, &c. 



Link * has published a series of excellent observations on 

 the uninterrupted and interrupted growth of wood in the stem, 

 as also on the growth of the leaves and root, which conclude 

 with a treatise on the anamorphoses of the stem and of the 

 root, which forms one of the most excellent parts of this new 

 edition of the Philosophia Botanica. This subject has nev^er 

 been treated of so specially and with such a profound knowledge. 



In a beautiful work also of G. Meneghinif several species 

 of monocotyledonous stems are anatomically characterized 

 with great accuracy, and explained by figures. I must how- 

 ever content myself with calling attention to these treatises, 

 as their contents are too voluminous to be given in this place. 

 I will here only give in full the results from this work of 

 Meneghini, which he himself has given in p. 77—86. 



'' Two ascertained facts," says the author, " in the vital ac- 

 tivity of monocotyledons, led me, in the observation of their 

 structure, to the conclusions, 1st, that, where certain currents 

 of vital saps exist, there also are vascular fibres formed ; and 

 that, 2ndly, certain curvatures are impressed on the interior 

 vascular fibres, by means of the displacements of the append- 

 ages of the stem from which these fibres are suspended." 



Meneghini proposed to himself for solution the following 

 problems : 



1. Which is the arrangement of the vascular fibres that 

 is common to all monocotyledonous stems ? 



• Elem. PhU. Bot. Ed. alt., p. 288—299. 



t Ricerche sulla Struttura del Caule nelle Piante Monocotiledoni. Padua, 

 1836, fol. niin. 



